List of previous requests

Sample description

Exclusions

Epoch-level exclusions

Epoch-level exclusions Freq Cumulative Freq Percent Cumulative Percent
1. Not in the sleep period 1364837 1364837 80.19 80.19
2. Missing veteran activity 547 1365384 0.03 80.22
3. Missing dog activity 35436 1400820 2.08 82.30
4. Missing Purdue sleep/wake classification 15 1400835 0.00 82.30
NA 301245 1702080 17.70 100.00

Night-level exclusions

Night-level exclusions Freq Cumulative Freq Percent Cumulative Percent
1. No veteran activity during the sleep period 1 1 0.15 0.15
2. No dog movement during the sleep period 25 26 3.70 3.85
NA 650 676 96.15 100.00

Proximity during the sleep period

Based on Bluetooth ping within prior 15 minutes

Minutes per night

Percent of the sleep period

Based on Morning Sleep Diary

Minutes per night with service dog in the room

Percent of the sleep period spent with service dog in the room

Minutes per night with service dog in the bed

Percent of the sleep period spent with service dog in the bed

Compare proximity based on Bluetooth with morning sleep diary

Minutes per night

Percent of the sleep period

Summary Tables

Minutes per night

Characteristic

N = 56

Bluetooth proximity, mean nightly minutes

Range

175, 543

Median (IQR)

396 (342, 443)

Mean (SD)

386 (81)

Service dog in the room, mean nightly minutes

Range

0, 579

Median (IQR)

393 (319, 465)

Mean (SD)

372 (135)

Missing

5

Service dog in the bed, mean nightly minutes

Range

0, 535

Median (IQR)

327 (86, 438)

Mean (SD)

274 (189)

Missing

5

Percent of the sleep period

Characteristic

N = 56

Bluetooth proximity, mean nightly percent

Range

38.4, 99.8

Median (IQR)

90.7 (80.6, 98.2)

Mean (SD)

86.8 (14.1)

Service dog in the room, mean nightly percent

Range

0.0, 100.0

Median (IQR)

95.5 (75.4, 100.0)

Mean (SD)

82.4 (27.2)

Missing

5

Service dog in the bed, mean nightly percent

Range

0.0, 100.0

Median (IQR)

81.8 (20.1, 100.0)

Mean (SD)

60.9 (40.3)

Missing

5

Sleep-wake concordance

Percent agreement

Cohen’s kappa

Kendall’s Tau

We want to characterize the extent to which the veteran and service dog were active at the same times during the night (without dichotomizing the activity data).

Challenges:

  • Different measures of activity for veterans and service dogs, with different scales/units
    • Veteran activity was collected with the Actiwatch-2/Actiware software.
    • Service dog activity was collected with the Whistle.
  • Zero-inflated activity data: Activity counts during the night are mostly zeros.
    • XX% of veteran epochs have an activity count equal to zero.
    • YY% of service dog epochs have an activity count equal to zero.

We can approach this by ranking the epoch-level activity data for the veteran, ranking the epoch-level activity data for the service dog, and then compare the ordering of the rankings each night to get a nightly measure of the extent to which the veteran and service dog were active during the same epochs.

Kendall’s tau is a measure of rank correlation. There are different versions of Kendall’s tau that handle ties in different ways. For most of the epochs the ranks are the same (i.e. due to zeros) for both the veteran and the dog, representing ties that need to be handled.

Pimentel, et al proposed an estimator based on Kendall’s tau for zero-inflated continuous variables. Perrone et al provided R code in Supplementary materials to calculate the estimator proposed by Pimentel et al, as well as their proposed estimator of Kendall’s tau for bivariate zero-inflated count data.

Summary Table

Characteristic

N = 56

Mean nightly percent agreement

Range

0.63, 0.88

Median (IQR)

0.80 (0.76, 0.83)

Mean (SD)

0.79 (0.05)

Mean nightly Cohen's kappa

Range

0.31, 0.85

Median (IQR)

0.73 (0.66, 0.78)

Mean (SD)

0.71 (0.10)

Mean nightly Kendall's Tau

Range

-0.02, 0.15

Median (IQR)

0.04 (0.03, 0.06)

Mean (SD)

0.04 (0.03)

Sleep-wake states - Summary Tables

Minutes per night

Characteristic

N = 56

Concordant - both sleeping, mean nightly minutes

Range

190, 449

Median (IQR)

330 (302, 368)

Mean (SD)

334 (60)

Concordant - both awake, mean nightly minutes

Range

5, 83

Median (IQR)

16 (12, 22)

Mean (SD)

18 (11)

Discordant - veteran sleep, dog awake, mean nightly minutes

Range

19, 89

Median (IQR)

46 (38, 56)

Mean (SD)

48 (16)

Discordant - veteran awake, dog sleeping, mean nightly minutes

Range

6, 115

Median (IQR)

43 (31, 60)

Mean (SD)

46 (22)

Percent of the sleep period

Characteristic

N = 56

Concordant - both sleeping, mean nightly percent

Range

45.4, 84.8

Median (IQR)

76.2 (70.9, 79.8)

Mean (SD)

74.8 (7.2)

Concordant - both awake, mean nightly percent

Range

1.2, 17.4

Median (IQR)

3.5 (2.6, 4.6)

Mean (SD)

3.9 (2.4)

Discordant - veteran sleep, dog awake, mean nightly percent

Range

4.2, 24.9

Median (IQR)

10.4 (9.0, 12.1)

Mean (SD)

10.8 (3.8)

Discordant - veteran awake, dog sleeping, mean nightly percent

Range

1.9, 26.4

Median (IQR)

9.8 (6.5, 12.7)

Mean (SD)

10.5 (5.2)

Exploratory analysis of human-animal bond and veteran health

Measures of veteran-canine bond

Inclusion of other in self

Monasch Dog Owner Relationship Scale

Lexington Attachment to Pets Scale

Measures of veteran health

PCL-5 Total Score

Fear of Sleep Inventory (FOSI)

Wake Transmission

Walters et al calculated four transmission variables.
1. Percent transmissions received: the percentage of an individual’s awakenings in a given time interval classified as a wake transmission (i.e., total number of transmitted wakes received by individual/total awakenings in individual).
2. Percent minutes resistant to transmission: percentage of a bedpartner’s nocturnal wake minutes during which an individual slept.
3. Number of transmissions received: the total number of transmission events in a given time interval.
4. Transmissibility: the percentage of the bedpartner’s awakenings in a given time interval that were classified as wake transmissions (i.e., number of wake transmissions received/total bedpartner awakenings: a measure of vulnerability to a bedpartner’s awakenings.

Reference:
- Walters, E. M., Phillips, A. J., Boardman, J. M., Norton, P. J., & Drummond, S. P. (2020). Vulnerability and resistance to sleep disruption by a partner: A study of bed-sharing couples. Sleep health, 6(4), 506-512.

Characteristic

N = 56

Percent transmissions received - veteran

Range

6.6, 32.7

Median (IQR)

13.8 (11.3, 18.6)

Mean (SD)

15.1 (5.7)

Percent transmissions received - service dog

Range

3.9, 49.0

Median (IQR)

22.2 (15.2, 25.8)

Mean (SD)

21.5 (9.2)

Percent minutes resistant to transmission - veteran

Range

40.3, 91.2

Median (IQR)

74.3 (68.6, 80.0)

Mean (SD)

73.3 (10.2)

Percent minutes resistant to transmission - service dog

Range

43.2, 87.4

Median (IQR)

72.1 (65.9, 77.5)

Mean (SD)

71.2 (9.2)

Number of transmissions received - veteran

Range

1.2, 6.8

Median (IQR)

3.3 (2.5, 4.4)

Mean (SD)

3.5 (1.4)

Number of transmissions received - service dog

Range

1.1, 15.1

Median (IQR)

6.0 (4.4, 8.5)

Mean (SD)

6.7 (3.2)

Transmissibility - veteran

Range

4.2, 20.9

Median (IQR)

10.1 (8.8, 13.5)

Mean (SD)

11.1 (3.5)

Transmissibility - service dog

Range

8.6, 82.1

Median (IQR)

25.5 (20.0, 32.5)

Mean (SD)

27.9 (13.0)